Resin composition and molded article

ABSTRACT

A resin composition including an aromatic polyether ketone resin (I), and a fluororesin (II), the fluororesin (II) being a copolymer of tetrafluoroethylene and a perfluoroethylenic unsaturated compound represented by the following formula (1):
 
CF 2 ═CF—R f   1   (1)
 
wherein R f   1  represents —CF 3  or —OR f   2 , and R f   2  represents a C1 to C5 perfluoroalkyl group; the composition containing the aromatic polyether ketone resin (I) and the fluororesin (II) at a mass ratio (I):(II) of 95:5 to 50:50; the fluororesin (II) being dispersed as particles in the aromatic polyether ketone resin (I) and having an average dispersed particle size of 3.0 μm or smaller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Rule 53(b) Continuation Application of U.S. application Ser.No. 14/341,588 filed Jul. 25, 2014 issued as U.S. Pat. No. 9,605,144,which is a Rule 53(b) Continuation Application of U.S. application Ser.No. 13/808,039 filed Jan. 2, 2013 issued as U.S. Pat. No. 8,829,130,which is a 371 of PCT International Application No. PCT/JP2011/064662filed Jun. 27, 2011, which claims benefit of Chinese Patent ApplicationNo. 201010218794.0 filed on Jul. 5, 2010. The above-noted applicationsare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a resin composition and a moldedarticle.

BACKGROUND ART

Switching from metal components to resin components has recently beenactively studied for the purposes of weight saving and cost reduction.The studies have led to practical use of vehicle components, industrialcomponents, and electrical and electronic components formed using athermoplastic resin such as a polyamide resin, a polycarbonate resin,and a polyacetal resin. Also for use as sliding members including gearsand bearing retainers, metal sliding members have been more and morereplaced by resin sliding members. These thermoplastic resins, however,are insufficient in sliding properties, as the sliding members are usedunder high load, high temperature, and high-speed rotation conditions.Thermoplastic resins therefore may cause problems such as wear, fusion,cracking, and chipping.

Meanwhile, fluororesins are excellent in sliding properties, heatresistance, chemical resistance, solvent resistance, weather resistance,flexibility, electrical properties, and other properties, and are thusused in a variety of fields including cars, industrial machines, OAequipment, and electrical and electronic equipment. Particularly,fluororesins have excellent sliding properties, and are one of theresins having a notably low friction coefficient. Fluororesins, however,have inferior mechanical properties and physical heat resistancerepresented by deflection temperature under load, compared tocrystalline heat-resistant thermoplastic resins in many cases. Also, insome cases, fluororesins have inferior dimensional stability compared toamorphous heat-resistant thermoplastic resins. Hence, the range of useof fluororesins has been limited.

Accordingly, thermoplastic resins have been studied for the purpose ofimproving their sliding properties and applying them to sliding membersin wider fields. For example, Patent Literature 1 discloses a resincomposition containing 1 to 50 parts by weight in total of a fluororesinand graphite for each 100 parts by weight of a resin composition thatconsists of 60 to 99 parts by weight of a thermoplastic resin having aheat deformation temperature of 100° C. or higher and 40 to 1 part byweight of carbon fibers. Patent Literature 2 discloses a resincomposition containing a thermoplastic resin (A) having a moldingtemperature of 300° C. or higher, and a polymer (B) obtained bypolymerization of an essential component of fluoroacryl α-fluoroacrylatethat has a specific structure.

Fluororesins are also known to be added to a thermoplastic resin forpurposes other than improvement of the sliding properties. For example,Patent Literature 3 discloses a technique of improving themold-processability, including decreasing the extrusion pressure andextrusion torque, in the mold-processing of engineering plastics. Thetechnique includes adding 0.005 to 1% by mass of a fluoropolymer basedon the total mass of the engineering plastics and the fluoropolymer.Patent Literature 4 discloses a technique of mixing PEEK resin finepowder in a water dispersion of a PFA resin at a PFA:PEEK weight ratioof 75:25 to 70:30, directly applying the dispersion to a roughened metalsurface in accordance with common methods, and baking the resultingproduct, so that a PFA-PEEK compound coating film having adhesiondurability is formed.

Polyether ether ketone (PEEK) resin has comparatively favorable slidingproperties among the thermoplastic resins, and thus has been put intopractical use for sliding members such as a gear and a bearing retainer.The sliding properties, however, are not sufficient under severe slidingconditions such as high load. To improve the sliding properties of PEEK,PEEK compositions containing PTFE powder were developed and areavailable. The PEEK compositions containing PTFE powder indeed have adecreased coefficient of kinetic friction, but have low slidingproperties which are represented by a limiting PV value. For thisreason, the sliding properties are desired to be further improved.

CITATION LIST Patent Literature

Patent Literature 1: JP H8-48887 A

Patent Literature 2: JP H10-195302 A

Patent Literature 3: WO 2003/044093

Patent Literature 4: JP H6-316686 A

SUMMARY OF INVENTION Technical Problem

The present invention therefore aims to provide a resin composition thatenables to obtain a molded article having both a low coefficient ofkinetic friction and a high limiting PV value.

Solution to Problem

The present inventors have found that the coefficient of kineticfriction and the limiting PV value greatly increase in the case that thefluororesin finely dispersed in an aromatic polyether ketone resin hasan average dispersed particle size in the order of thousands ofnanometers.

That is, one aspect of the present invention is a resin compositionincluding

an aromatic polyether ketone resin (I), and

a fluororesin (II),

the fluororesin (II) being a copolymer of tetrafluoroethylene and aperfluoroethylenic unsaturated compound represented by the followingformula (1):CF₂═CF—R_(f) ¹  (1)

wherein R_(f) ¹ represents —CF₃ or —OR_(f) ², and R_(f) ² represents aC1 to C5 perfluoroalkyl group;

the composition including the aromatic polyether ketone resin (I) andthe fluororesin (II) at a mass ratio (I):(II) of 95:5 to 50:50;

the fluororesin (II) being dispersed as particles in the aromaticpolyether ketone resin (I) and having an average dispersed particle sizeof 3.0 μm or smaller.

The fluororesin (II) preferably has an average dispersed particle sizeof 0.30 μm or smaller.

The fluororesin (II) preferably has a melt flow rate of 0.1 to 100 g/10min.

The aromatic polyether ketone resin (I) is preferably a polyether etherketone.

Another aspect of the present invention is a molded article includingthe above resin composition.

The molded article can be used as a sliding member. Particularly, themolded article can be used, for example, as a sealant, gear, actuator,piston, bearing, or bushing.

Advantageous Effects of Invention

Since the resin composition of the present invention has the abovestructure, a molded article having a low coefficient of kinetic frictionand a high limiting PV value can be obtained. The molded article to beobtained also has excellent sliding properties.

DESCRIPTION OF EMBODIMENTS

The present invention is described in detail below.

The present invention relates to a resin composition containing anaromatic polyether ketone resin (I) and a fluororesin (II).

The above aromatic polyether ketone resin (I) is preferably at least oneselected from the group consisting of polyether ketone, polyether etherketone, polyether ketone ketone, and polyether ketone ether ketoneketone. The aromatic polyether ketone resin (I) is more preferably atleast one selected from the group consisting of polyether ketone andpolyether ether ketone, and still more preferably polyether etherketone.

The above aromatic polyether ketone resin (I) preferably has a meltviscosity of 0.05 to 0.50 kNsm⁻² at 1000 sec⁻¹ and 400° C. A meltviscosity in the above range can improve the processing properties,leading to a low coefficient of kinetic friction and a high limiting PVvalue. The lower limit of the melt viscosity is preferably 0.10 kNsm⁻².The upper limit of the melt viscosity is preferably 0.45 kNsm⁻².

The aromatic polyether ketone resin (I) preferably has a glasstransition temperature of 130° C. or higher, more preferably 135° C. orhigher, and still more preferably 140° C. or higher. A glass transitiontemperature in the above range enables to obtain a resin compositionhaving excellent heat resistance. The glass transition temperature ismeasured by a differential scanning calorimetry (DSC).

The aromatic polyether ketone resin (I) preferably has a melting pointof 300° C. or higher, and more preferably 320° C. or higher. A meltingpoint in the above range enables to improve the heat resistance of themolded article to be obtained. The melting point is measured by adifferential scanning calorimetry (DSC).

The fluororesin (II) is a copolymer of tetrafluoroethylene (TFE) and aperfluoroethylenic unsaturated compound represented by the followingformula (1):CF₂═CF—R_(f) ¹  (1)

wherein R_(f) ¹ represents —CF₃ or —OR_(f) ², and R_(f) ² represents aC1 to C5 perfluoroalkyl group. The fluororesin (II) may be onefluororesin or two or more fluororesins. In the case that the R_(f) ¹ is—OR_(f) ², the R_(f) ² is preferably a C1 to C3 perfluoroalkyl group.

The perfluoroethylenic unsaturated compound represented by formula (1)is preferably at least one selected from the group consisting ofhexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethylvinyl ether), and perfluoro(propyl vinyl ether), and more preferably atleast one selected from the group consisting of hexafluoropropylene andperfluoro(propyl vinyl ether).

The fluororesin (II) is preferably a perfluoropolymer, for a lowcoefficient of kinetic friction.

The fluororesin (II) preferably consists of 90 to 99 mol % of TFE and 1to 10 mol % of the perfluoroethylenic unsaturated compound representedby formula (1). More preferably, the fluororesin (II) consists of 93 to99 mol % of TFE and 1 to 7 mol % of the perfluoroethylenic unsaturatedcompound represented by formula (1).

The fluororesin (II) preferably has a melt flow rate (MFR) of 0.1 to 100g/10 min, and more preferably 10 to 40 g/10 min when measured at 372° C.under a load of 5000 g. An MFR in the above range enables to decreasethe coefficient of kinetic friction of the molded article to be producedfrom the resin composition of the present invention, and also thelimiting PV value can be improved. The lower limit of the MFR is stillmore preferably 12 g/10 min, and particularly preferably 15 g/10 min.The upper limit of the MFR is still more preferably 38 g/10 min, andparticularly preferably 35 g/10 min from the viewpoint of reducing thecoefficient of kinetic friction.

The fluororesin (II) may have any melting point, but preferably has amelting point equal to or lower than the melting point of the aromaticpolyether ketone resin (I) because the fluororesin (II) in molding ispreferred to be already melt at the temperature where the aromaticpolyether ketone resin (I) used in the molding is molten. For example,the melting point of the fluororesin (II) is preferably 230° C. to 350°C.

The fluororesin (II) may have been treated with fluorine gas or ammoniaby a common method.

The resin composition of the present invention contains the aromaticpolyether ketone resin (I) and the fluororesin (II) at a mass ratio(I):(II) of 95:5 to 50:50. A ratio in the above range enables to producea molded article that has both a low coefficient of kinetic friction anda high limiting PV value. A mass ratio of the amount of the fluororesin(II) to the aromatic polyether ketone resin (I) of more than 50 islikely to decrease the strength, while a mass ratio of less than 5 maynot achieve a sufficient coefficient of kinetic friction. The mass ratiois more preferably in the range of 90:10 to 60:40.

The fluororesin (II) in the resin composition of the present inventionis dispersed as particles in the aromatic polyether ketone resin (I),and has an average dispersed particle size of 3.0 μm or smaller. Toolarge an average dispersed particle size leads to insufficient slidingproperties. The lower limit may be any value, and may be 0.01 μm.

The average dispersed particle size of the fluororesin (II) ispreferably 2.0 μm or smaller. An average dispersed particle size of 2.0μm or smaller enables to obtain a molded article having a high limitingPV value.

The average dispersed particle size of the fluororesin (II) is morepreferably 1.0 μm or smaller.

To prevent cracking and chipping of sliding members, aromatic polyetherketone having better impact resistance has always been desired. Atechnique of forming an alloy with a rubber component is commonlyemployed to improve the impact resistance of thermoplastic resins. Anaromatic polyether ketone, however, is a thermoplastic resin having highheat resistance with a mold-processing temperature of higher than 350°C. These aromatic polyether ketones are typically molded at around 400°C. If the aromatic polyether ketone is alloyed with a rubber component,the rubber component will be deteriorated by heat during moldprocessing, which is not practical. Effective ways to improve the impactresistance of aromatic polyether ketones have not actually been found.

The present inventors have found that an average dispersed particle sizeof the fluororesin (II) of 1.0 μm or smaller not only enables to obtaina molded article having both a low coefficient of kinetic friction and ahigh limiting PV value, but also unexpectedly causes great improvementof the impact resistance of the molded article.

The average dispersed particle size of the fluororesin (II) is stillmore preferably 0.30 μm for obtaining a molded article having betterimpact resistance.

The average dispersed particle size of the fluororesin (II) can bedetermined by microscopically observing a pressed sheet of the resincomposition of the present invention by a transmission electronmicroscope (TEM), and binarizing the obtained image by an opticalanalysis device.

The resin composition of the present invention contains the aromaticpolyether ketone resin (I) and the fluororesin (II), and may optionallyfurther contain other component(s). The other component(s) may be any ofthe components including fibrous reinforcing agents such as whiskers(e.g. potassium titanate whiskers), glass fibers, asbestos fibers,carbon fibers, ceramic fibers, potassium titanate fibers, aramid fibers,and other high-strength fibrous reinforcing agents; inorganic fillerssuch as calcium carbonate, talc, mica, clay, carbon powder, graphite,and glass beads; colorants; commonly used inorganic or organic fillerssuch as flame retardants; stabilizers such as minerals and flakes;lubricants such as silicone oil and molybdenum disulfide; pigments;conducting agents such as carbon black; impact resistance improvers suchas rubber; and other additives.

The resin composition of the present invention may be produced by anymethod under ordinary conditions, using a mixer typically used formixing resin compositions such as a composition for molding. Examples ofthe mixer include mixing mills, Banbury mixers, pressure kneaders, andextruders. The mixer is preferably a twin screw extruder, particularly atwin screw extruder that has a screw structure with a large L/D.

Examples of the method of producing the resin composition of the presentinvention include a method of mixing the aromatic polyether ketone resin(I) and the fluororesin (II) in a molten state.

Sufficient kneading of the aromatic polyether ketone resin (I) and thefluororesin (II) can give the desired dispersion state to the resincomposition of the present invention. The dispersion state affects thecoefficient of kinetic friction and limiting PV value of the moldedarticle, and thus an appropriate mixing method should be selected toachieve the desired dispersion state in the pressed sheet to be obtainedfrom the resin composition.

Examples of the method of producing the resin composition of the presentinvention include a method of charging a mixer with the aromaticpolyether ketone resin (I) and the fluororesin (II) at a proper ratio,optionally adding the above other component(s), and melt-kneading theresins (I) and (II) at their melting points or higher.

The other component(s) may be mixed independently with the aromaticpolyether ketone resin (I) and the fluororesin (II) before the kneadingof the resins (I) and (II), or may be mixed with the aromatic polyetherketone resin (I) and the fluororesin (II) when these resins are mixed.

The temperature for the melt-kneading may be appropriately determineddepending on the conditions such as the kinds of the aromatic polyetherketone resin (I) and the fluororesin (II) to be used. Preferably, thetemperature is 360° C. to 400° C., for example. The kneading time isusually one minute to one hour.

The resin composition can give a molded article having a coefficient ofkinetic friction of 0.21 or less. A coefficient of kinetic friction inthe above range allows its molded article to be suitable for use as asliding member.

The resin composition can give its molded article a limiting PV value of800 or higher, more preferably 1300 or higher, and still more preferably1500 or higher.

The resin composition can give a notched Izod strength of 30 kJ/m² orhigher to its molded article. The notched Izod strength is preferably 40kJ/m² or higher. For a high Izod strength, the average dispersedparticle size of the fluororesin (II) should be controlled to 1.0 μm orsmaller.

A molded article formed from the resin composition of the presentinvention is another aspect of the present invention.

The molded article formed from the resin composition of the presentinvention has, in addition to the sliding properties and the impactresistance, heat resistance, chemical resistance, solvent resistance,strength, rigidity, low chemical agent permeability, dimensionalstability, flame retardancy, electrical properties, and durability. Inthe electrical, electronic, and semiconductor fields, the molded articlecan be used for components of semiconductor and liquid crystal devicemanufacturing devices (e.g. a CMP retainer ring, an etching ring, asilicon wafer carrier, and an IC chip tray), insulating films, smallbutton cells, cable connectors, and aluminum electrolytic condenser bodycasings. In the automobile field, the molded article can be used forthrust washers, oil filters, gears for auto air-conditioner controllingunits, gears of throttle bodies, ABS parts, AT seal rings, MT shift forkpads, bearings, seals, and clutch rings. In the industrial field, themolded article can be used for compressor components, cables of a masstransport system, conveyor belt chains, connectors for oil fielddevelopment machinery, and pump components of a hydraulic pressuredriver system (e.g. bearings, port plates, ball joints of a piston). Inthe aerospace field, the molded article can be used for interiorcomponents in an aircraft cabin, wire covering, cable protection, andfuel pipe protecting materials. The molded article can also be used forother products such as food and beverage production equipmentcomponents, and medical instruments (e.g. sterile instruments, gas andliquid chromatographs).

The molded article may have any of a variety of shapes, such as acoating material shape, sheet shape, film shape, rod shape, and pipeshape.

Another aspect of the present invention is a molded article for asliding member obtained from the resin composition. A molded article fora sliding member which is formed from the above resin composition has alow coefficient of kinetic friction, and thus is suitable for use as asliding member. Since the molded article contains a fluororesin, themolded article is also excellent in properties such as chemicalresistance, weather resistance, non-adhesiveness, water repellence, andelectrical properties. Examples of the molded article for slidingmembers include, but not particularly limited to, sealants, gears,actuators, pistons, bearings, bearing retainers, bushings, switches,belts, bearings, cams, rollers, and sockets.

The molding machine in the method of producing a molded article may beused with the known parameters, for example, or any other parameters.The molding temperature is usually preferred to be equal to or higherthan the melting point of the aromatic polyether ketone resin (I) to beused. Also, the molding temperature is preferred to be lower than thelower temperature of the decomposition temperature of the fluororesin(II) and the decomposition temperature of the aromatic polyether ketoneresin (I). The molding temperature may be, for example, 250° C. to 400°C.

The molded article of the present invention can be formed by a moldingmethod commonly used for a thermoplastic resin composition, such as theinjection molding, extrusion molding, press molding, blow molding,calender molding, and casting molding, depending on the kind, use, andshape of the molded article to be obtained. The molded article may alsobe produced by a molding method which is a combination of the abovemolding methods. The molded article may be obtained through compositemolding of the resin composition of the present invention and otherpolymer(s).

EXAMPLES

The present invention is described in the following examples. Thepresent invention is not limited to these examples.

Measurement of MFR

In accordance with ASTM D3307-01, the mass (g/10 min) of the polymerflowing out from the nozzle (inner diameter: 2 mm, length: 8 mm) of amelt indexer (product of Toyo Seiki Seisaku-sho, Ltd.) at 372° C. undera load of 5000 g was determined.

Production of Pressed Sheet Molded Article

The resin compositions produced in the examples and comparative exampleseach were compression molded in a heat press molding machine at 380° C.and 5 MPa, so that 3-mm-thick sheets were produced.

Determination of Limiting PV Value

Each pressed sheet obtained by the above method was cut into a 3 cm(length)×3 cm (width)×3 mm (thickness) specimen. The limiting PV valueof the specimen was determined in accordance with the A method of JISK7218, using a friction and wear tester (product of A&D Company,Limited) and a steel material S45C (#240 sandpaper finishing) as anopposite material. The speed was constant at 3 m/sec, and the surfacepressure was increased by 20 N from 20 N every 10 minutes.

Measurement of Coefficient of Kinetic Friction

The coefficient of kinetic friction of the pressed sheet obtained by themethod described above was determined using a ball-on-disk SRV frictionwear tester (product of OPTIMOL) at room temperature and 50 Hz.

Measurement of Notched Izod Strength

In accordance with JIS K7110, a specimen for notched Izod strengthmeasurement was cut out from the pressed sheet produced by the methoddescribed above, and the notched Izod strength was measured at roomtemperature using an Izod impact tester (product of Toyo SeikiSeisaku-sho, Ltd.).

Calculation of Average Dispersed Particle Size

The pressed sheet produced by the method described above was trimmed tohave a 1-mm-square tip by a razor for trimming. The sheet was then fixedin the sample holder of an ultramicrotome (ULTRACUT S, product of LeicaMicrosystems), and the chamber was cooled with liquid nitrogen to −80°C. inside. Thereby, a 90-nm-thick ultrathin section was cut out from thespecimen. The ultrathin section obtained was taken out using a platinumring to which a 20% ethanol solution was deposited. The ultrathinsection was adhered to a copper mesh sheet (product of Okenshoji Co.,Ltd., 200 A, ϕ3.0 mm).

The ultrathin section adhered to the copper mesh sheet was observedusing a transmission electron microscope (H7100FA, product of Hitachi,Ltd.).

A negative film obtained through the microscopic observation was scannedinto an electronic image using a scanner (GT-9400UF, product of EPSON).The electronic image was binarized by an optical analyzer (LUZEX AP,product of Nireco), so that the average dispersed particle size of thedispersed phase was determined.

The following materials were used in the examples and comparativeexamples.

Aromatic polyether ketone resin (I): Polyether ether ketone (trade name:450G, product of Victrex Japan Inc.)

Fluororesin (II-1): Tetrafluoroethylene/hexafluoropropylene copolymer(composition weight ratio:tetrafluoroethylene/hexafluoropropylene/perfluoro(propyl vinylether)=87.5/11.5/1.0, MFR: 27 g/10 min)

Fluororesin (II-2): Tetrafluoroethylene/perfluoroalkyl vinyl ethercopolymer (composition weight ratio:tetrafluoroethylene/perfluoro(propyl vinyl ether)=94.5/5.5, MFR: 23 g/10min)

Fluororesin (III): Polytetrafluoroethylene (trade name: LUBRON L5,product of Daikin Industries, Ltd.)

Fluororesin (IV): Ethylene/tetrafluoroethylene copolymer (trade name:Neoflon EP541, product of Daikin Industries, Ltd.)

Examples 1 and 2

A melt-kneading device (trade name: Labo Plastomill, product of ToyoSeiki Seisaku-sho, Ltd.) was charged with the aromatic polyether ketoneresin (I) and the fluororesin (II) at the ratio (parts by mass) shown inTable 1. The materials were melt-kneaded for 10 minutes at a temperatureof 380° C. and a screw rotational speed of 80 rpm, whereby a resincomposition was produced. The obtained resin composition was formed intoa pressed sheet by the method described above, and the limiting PVvalue, coefficient of kinetic friction, and notched Izod strength of thesheet were determined. Also, an ultrathin section was cut out from thepressed sheet, so that the average dispersed particle size of thefluororesin (II) was calculated.

Examples 3 to 6

The aromatic polyether ketone resin (I) and the fluororesin (II) werepreliminarily mixed at the ratio (parts by mass) shown in Table 1. Then,the mixture was melt-kneaded by a twin screw extruder (ϕ15 mm, L/D=60)at a cylinder temperature of 380° C. and a screw rotation speed of 350rpm, whereby a resin composition was produced. The obtained resincomposition was formed into a specimen by the method described above,and the limiting PV value, coefficient of kinetic friction, and notchedIzod strength were determined. The average dispersed particle size ofthe fluororesin (II) was also calculated.

Comparative Example 1

A specimen was produced by the method described above from only thearomatic polyether ketone resin (I), and the limiting PV value,coefficient of kinetic friction, and notched Izod strength weredetermined.

Comparative Examples 2 and 3

The aromatic polyether ketone resin (I) and the fluororesin (III) orfluororesin (IV) were preliminarily mixed at the ratio (parts by mass)shown in Table 1. Then, the mixture was melt-kneaded by a twin screwextruder (ϕ15 mm, L/D=60) at a cylinder temperature of 380° C. and ascrew rotation speed of 350 rpm, whereby a resin composition wasproduced. The obtained resin composition was formed into a pressed sheetby the method described above, and the limiting PV value, coefficient ofkinetic friction, and notched Izod strength were determined. Also, anultrathin section was cut out from the pressed sheet, so that theaverage dispersed particle size of the fluororesin (II) was calculated.

TABLE 1 Comparative Comparative Comparative Example 1 Example 2 Example3 Example 4 Example 5 Example 6 Example 1 Example 2 Example 3 Polyetherketone resin (I) 80 80 80 60 80 60 100 80 80 Fluororesin (II-1) 20 20 40Fluororesin (II-2) 20 20 40 Fluororesin (III) 20 Fluororesin (IV) 20Average dispersed particle 1.54 1.90 0.13 0.22 0.18 0.25 — 73 2.80 size(μm) Limiting PV value (kPa · m/s) 900 1000 1500 1600 1700 1950 750 600750 Coefficient of kinetic friction 0.21 0.19 0.18 0.16 01.17 0.15 0.240.15 0.23 Notched Izod strength (kJ/m²) 17 17 55 70 50 70 17 18 15

The results of Comparative Example 3 show that use of anethylene/tetrafluoroethylene copolymer as a fluororesin improves neitherthe coefficient of kinetic friction nor the wear resistance. Addition ofpolytetrafluoroethylene decreased the coefficient of kinetic friction asseen from the results of Comparative Example 2, but did not affect thewear resistance.

INDUSTRIAL APPLICABILITY

The resin composition of the present invention is suitable for moldingmaterials used for components such as automobile components, industrialcomponents, and electrical and electronic components which are requiredto have high sliding properties.

The invention claimed is:
 1. A resin composition comprising an aromaticpolyether ketone resin (I), and a fluororesin (II), the fluororesin (II)being a copolymer of tetrafluoroethylene and a perfluoroethylenicunsaturated compound represented by the following formula (1):CF₂═CF—R_(f) ¹  (1) wherein R_(f) ¹ represents —CF₃ or —OR_(f) ², andR_(f) ² represents a C1 to C5 perfluoroalkyl group; the compositioncomprising the aromatic polyether ketone resin (I) and the fluororesin(II) at a mass ratio (I):(II) of 95:5 to 50:50; the fluororesin (II)being dispersed as particles in the aromatic polyether ketone resin (I)and having an average dispersed particle size of 1.9 μm or smaller. 2.The resin composition according to claim 1, wherein the fluororesin (II)has an average dispersed particle size of 0.30 μm or smaller.
 3. Theresin composition according to claim 1, wherein the fluororesin (II) hasa melt flow rate of 0.1 to 100 g/10 min when measured at 370° C. under aload of 5000 grams.
 4. The resin composition according to claim 1,wherein the aromatic polyether ketone resin (I) is a polyether etherketone.
 5. A molded article comprising the resin composition accordingto claim
 1. 6. The molded article according to claim 5, for use as asliding member.
 7. The molded article according to claim 5, which is asealant, gear, actuator, piston, bearing, or bushing.
 8. A resincomposition comprising an aromatic polyether ketone resin (I), and afluororesin (II), the fluororesin (II) being a copolymer oftetrafluoroethylene and a perfluoroethylenic unsaturated compoundrepresented by the following formula (1):CF₂═CF—R_(f) ¹  (1) wherein R_(f) ¹ represents —CF₃ or —OR_(f) ², andR_(f) ² represents a C1 to C5 perfluoroalkyl group; the compositioncomprising the aromatic polyether ketone resin (I) and the fluororesin(II) at a mass ratio (I):(II) of 95:5 to 50:50; the aromatic polyetherketone resin (I) having a melt viscosity of 0.05 to 0.50 kNsm⁻¹ at 1000sec⁻¹ and 400° C.; the fluororesin (II) being dispersed as particles inthe aromatic polyether ketone resin (I) and having an average dispersedparticle size of 1.9 μm or smaller; and the fluororesin (II) having amelting point equal to or lower than that of the aromatic polyetherketone resin (I).
 9. A molded article comprising the resin compositionaccording to claim 8, wherein a molding temperature is lower than thelower of the decomposition temperature of the fluororesin (II) and thedecomposition temperature of the aromatic polyether ketone resin (I).10. The resin composition according to claim 1, wherein a molded articleobtained from the resin composition has a limiting PV value of 800kPa·m/s or higher.
 11. The resin composition according to claim 8,wherein a molded article obtained from the resin composition has alimiting PV value of 800 kPa·m/s or higher.
 12. The resin compositionaccording to claim 1, wherein a molded article obtained from the resincomposition has a limiting PV value of 1000 kPa·m/s or higher.
 13. Theresin composition according to claim 8, wherein a molded articleobtained from the resin composition has a limiting PV value of 1000kPa·m/s or higher.
 14. The resin composition according to claim 1,wherein a molded article obtained from the resin composition has alimiting PV value of 1300 kPa·m/s or higher.
 15. The resin compositionaccording to claim 8, wherein a molded article obtained from the resincomposition has a limiting PV value of 1300 kPa·m/s or higher.
 16. Theresin composition according to claim 1, which comprises the aromaticpolyether ketone resin (I) and the fluororesin (II) at a mass ratio(I):(II) of 90:10 to 50:50.
 17. The resin composition according to claim8, which comprises the aromatic polyether ketone resin (I) and thefluororesin (II) at a mass ratio (I):(II) of 90:10 to 50:50.
 18. Theresin composition according to claim 1, wherein the fluororesin (II) hasan average dispersed particle size of 1.0 μm or smaller.
 19. The resincomposition according to claim 8, wherein the fluororesin (II) has anaverage dispersed particle size of 1.0 μm or smaller.